Rafael A. Rivera Soto

Rafael A. Rivera Soto

Researcher at LLNL | PhD Candidate at JHU

I am a researcher at Lawrence Livermore National Laboratory (LLNL) and a PhD candidate at Johns Hopkins University (JHU-CLSP), advised by Nicholas Andrews.

My research focuses on natural language processing, with emphasis on machine-text detection, authorship analysis, and representation learning. I am particularly interested in understanding and detecting the stylistic signatures of language models, and in developing robust methods for attributing text to its source.

Previously, I obtained my M.S. in Computer Science from UC Davis, where I worked with Yong Jae Lee on real-time instance segmentation.

Google Scholar GitHub

Gem Cutting

Gem 1
Lab Sapphire in Jeff Graham's Portuguese design
Gem 2
Lab Sapphire in Marco Voltolini's Tensor design
Gem 3
Lab Ruby in Arya Akhavan's Void Reaver design

Selected Publications

  1. Unsupervised Style Representation Learning for AI-Text Detection via Paraphrase Inversion

    Rafael A. Rivera Soto, Barry Y. Chen, Nicholas Andrews

    preprint, 2026

    arXiv

  2. Attacks on Machine-Text Detectors Retain Stylistic Fingerprints

    Rafael A. Rivera Soto, Barry Y. Chen, Nicholas Andrews

    ICML 2026

    arXiv

  3. A Survey on Representing Linguistic Style: Challenges and Opportunities

    Anna Wegmann, Cristina Aggazzotti, Rafael Rivera Soto, Dong Nguyen

    preprint, 2026

    PDF

  4. Mitigating Paraphrase Attacks on Machine-Text Detection via Paraphrase Inversion

    Rafael A. Rivera Soto, Barry Y. Chen, Nicholas Andrews

    ACL Findings, 2025

    arXiv

  5. Few-Shot Detection of Machine-Generated Text using Style Representations

    Rafael A. Rivera Soto, Kailin Koch, Aleem Khan, Barry Y. Chen, Marcus Bishop, Nicholas Andrews

    ICLR, 2024

    arXiv Code Demo

  6. Can Authorship Representation Learning Capture Stylistic Features?

    Andrew Wang, Cristina Aggazzotti, Rebecca Kotula, Rafael A. Rivera Soto, Marcus Bishop, Nicholas Andrews

    TACL, 2023

    arXiv

  7. Learning Universal Authorship Representations

    Rafael A. Rivera Soto, Olivia Elizabeth Miano, Juanita Ordonez, Barry Y. Chen, Aleem Khan, Marcus Bishop, Nicholas Andrews

    EMNLP, 2021

    PDF Code

  8. YolactEdge: Real-time Instance Segmentation on the Edge

    Haotian Liu, Rafael A. Rivera Soto, Fanyi Xiao, Yong Jae Lee

    ICRA, 2021

    arXiv Code